Cause of iron staining?


New member
May 24, 2019
Oswego, NY
Hi all!

First time poster, long time reader. I’ve owned my 24’ above ground pool for 7 years. I noticed discoloration on the liner after opening the pool this year and eventually discovered it was iron staining. I’m most of the way through a successful ascorbic acid/sequestrant treatment. My main concern is the cause of the staining (it was quite extensive). My initial thought was that is was due to a rusting bolt that was screwed into the filter where the pressure gauge use to be. Ive since replaced the bolt with a proper gauge. The bolt was so rusted the top broke off when I removed it. Anyways, I’m curious if a rusty bolt could cause such extensive staining. I have municipal water which I know could contain iron but is less likely than well water. I’m hoping it was the bolt and that once I remove the current iron, I’ll be good to go without always adding sequestrant. I have a culator on the way to help remove the metal and there was also sediment after AA treatment which I vacuumed to waste. Any thoughts? Before and after photos are attached to show staining.



Gold Supporter
TFP Guide
Jul 21, 2013
Northern NJ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Try running your pool water though polyfill for a while and see what it picks up.

I doubt one rusting bolt will cause that much staining. Hard to say where the iron came from.